code: def test_cross_device():
      if torch.cuda.device_count() > 1:
          for src in [0, 1]:
              for dst in [0, 1]:
                  yield _test_cross_device, src, dst
  
file_path: DALI/dali/test/python/test_external_source_pytorch_gpu.py
imports: from nose.plugins.attrib import attr
  from nvidia.dali.pipeline import Pipeline
  import nvidia.dali.fn
  from test_utils import check_output
  import torch
  from test_external_source_impl import use_torch
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: test_cross_device() without return types